The Surveillance, Epidemiology, and End Results (SEER) Program of the National Cancer Institute (NCI) is an authoritative source of information on cancer incidence and survival in the United States. SEER currently collects and publishes cancer incidence and survival data from population-based cancer registries covering approximately 26 percent of the US population. SEER coverage includes 23 percent of African Americans, 40 percent of Hispanic Americans, 42 percent of American Indians and Alaska Natives, 53 percent of Asians, and 70 percent of Hawaiian and Pacific Island Americans. The current SEER data maintained at NCI includes records on 5.4 million cancers. The database serves as important resource for reporting on the burden of cancer, and is utilized by researchers both within and outside of NCI for the purpose of conducting descriptive epidemiologic studies. The SEER Program is a core component of the NCI's surveillance activities which provide information used for planning cancer control and research programs, and for evaluating the impact of such programs on cancer rates. The SEER Program was initiated in 1972 in response to requirements of the National Cancer Program for assessing the magnitude of the cancer burden in the United States, and for identifying factors related to cancer risk and/or patient survival. The SEER Program has among its objectives: 1. To assemble and report, on a periodic basis, estimates of cancer incidence, especially among the following key cancer sites: breast cancer, lung cancer, colorectal cancer, prostate cancer, pancreatic cancer, and urinary bladder cancer. 2. To monitor annual cancer incidence trends to identify unusual changes in specific forms of cancer occurring in population subgroups defined by geographic, demographic, and social characteristics. 3. To provide continuing information on changes over time in extent of disease at diagnosis, trends in therapy, and changes in cancer patient survival. 4. To identify the occurrence of possible iatrogenic cancers, i.e., cancers that are caused by cancer therapy. 5. To serve as a research resource to the National Cancer Institute, and conduct studies dealing with current cancer control issues as well as problems related to the operation of the SEER Program.